Azo pigments and method of producing



Patented Nov. 30, 1943 AZO PIGMENTS AND METHOD OF PRODUCING William B.Reynolds, Cincinnati, Ohio, assignor to Interchemical Corporation, NewYork, N. Y., a corporation of Ohio No Drawing. Application November 14,1942, Serial No. 465,630

2 Claims.

This invention relates to azo pigments, and has particular reference tonew pigments, characterized by brilliance of tone combined with fastnessto light and resistance to bleeding in organic solvents. Specifically,this invention relates to the coppery complexes obtainable from thecouplings of beta-oxy naphthoic acid with diazotized primary aromaticmono-amines.

There has been considerable demand, particularly in the field of pigmentprinting on textiles, for pigments which would combine the features ofbrilliance of tone, fastness to light, and resistance to solvents suchas acetone, while showing extremely good resistance to water and dilutesoap solutions. In particular, acceptable browns and violets have beendifficult to obtain unless insoluble vat dyestufis are used.

In my copending application Serial Number 340,096, filed June 12, 1940,of which this is a continuation in part, I have disclosed the discoveryof certain azo pigments which combine brilliance of tone, exceptionallygood light fastness, and resistance to solvents with wash fastness.These pigments comprise the coppered complexes of the couplings ofbeta-oxy naphthoic acid with diazotized primary aromatic amines of thegeneral formula XnRNHZ, where R is a benzene or naphthalene nucleus, Xis any substituent of the group consisting of alkyl, alkoxy, halogen andnitro, and n is a number from to 3. It is therein stated that aryl andaralkyl substituents may be employed, without any specific disclosure ofcompounds containing such groups.

This disclosure is directed to pigments which comprise the copperedcomplexes of the couplings of beta oxy naphthoic acid with diazotizedamines of the general formula XnRNHZ, where X is a substituent of thegroup consisting of alkyl and aralkyl, R. is a benzene or naphthalenenuleuc, and n is a number from 1 to 3.

These pigments range in color from deep violet to brown, and areparticularly desirable as substitutes for the more expensive insolublevat dyestuffs where pigment printing is being done.

These new pigments can be represented by the general formula:

COOH

where R is a benzene or naphthalene nucleus, X is any substituent of thegroup consisting of aryl and aralkyl, and n is a number from 0 to 3.

Typical amines which can be used include 2,amino biphenyl, 4-aminobiphenyl, 4-aminol,l'binaphthyl, 4-phenyl-1-naphthylamine, 2,4- diphenylaniline, 2,4,6-triphenyl aniline, p-benzyl aniline, p-amino bibenzyl,and. l-benzyl-lnaphthylamine, and certain other amines similar to theabove but containing alkoxy, halogen, or nitro substituents in one ormore of the aromatic nuclei.

Typical examples of my invention are the following:

16.9 grams (.1 M) ortho amino diphenyl was diazotized in the usualmanner using .25 M hydrochloric acid, .1 M sodium nitrite and water. Theresulting diazo solution was coupled to a solution made by dissolving18.8 grams (.1 M) beta oxy naphthoic acid with 4 grams (.1 M) sodiumhydroxide, 1500 cc. water and ice (total), 31.8 grams (.3 M) sodiumcarbonate (100%).

The red pigment was filtered, washed alkali free, reslurried with about1500 cc. water, heated to C. and treated with the following solution,also at 60 0.:

74.85 gms. (.3 M) copper sulfate (5 molecules water) dissolved in 200cc. water, and the copper compound precipitated and redissolved withammonium hydroxide. The mixture was then heated to and maintained nearthe boil for one hour, filtered and washed alkali-free.

The typical precautionary measures useful in diazotization reactionsshould be observed, these varying of course with the particular amine.In coupling, I prefer to operate with the beta oxy naphthoic acidpartially out of solution, as I find that improved results are obtainedin more concentrated coupling solutions.

The copper probably couples by forming a complex between the phenolichydroxyl and the carboxyl group. I find that about 10 to 15% excess ofcopper is desirable over that necessary to produce the theoreticalequi-molar complex with the beta-oxy naphthoic acid (i. e. one mol ofcop-, per per mol of dyestuff). The coppering can take place in neutralor alkaline solutions (pH 7.0 or higher), the copper may be present as asimple salt, or as a complex such as the copper ammonium complex. Ingeneral, rather elevated temperatures (60-100" C.) are necessary toinsure complete coppering.

Obviously, many changes can be made in the specific examples, withoutdeparting from the scope of the invention, which is defined in theclaims.

I claim:

1. As new pigment dyestuffs, the water-insoluble compounds of thegeneral formula:

X,.R-N=N Cu ooon where R is a nucleus of the group consisting of benzeneand naphthalene nuclei free of watersolubilizing substituents, X is asubstituent of

